1. Field
One embodiment of the invention relates to an image processing apparatus and an image processing method which carry out the process of sharpening images.
2. Description of the Related Art
Recently, opportunities to view video content on a personal computer display whose resolution exceeds that specified in the Standard-Definition (SD) standard have been increasing. As high-definition broadcasting has been getting into full swing, a High-Definition (HD) standard-compatible television receivers have been becoming popular in ordinary households.
Compared with such a high-resolution video display unit, video data obtained by an image pickup apparatus, such as a video camera, television broadcast complying with the SD standard, and DVDs are low in resolution. Therefore, it is necessary to increase the resolution of video data using suitable means. In addition, when an image is partially enlarged and displayed or when filming is performed by digital zoom exceeding optical zoom with a video camera, the resolution has to be increased.
To increase resolution, linear interpolation or interpolation by cubic convolution has been used. However, this has caused the problem of being incapable of obtaining sufficient sharpness. Jpn. Pat. Appln. KOKAI Publication No. 2008-067110 and Jpn. Pat. Appln. KOKAI Publication No. 2008-146190 have disclosed super-resolution techniques for creating an image exceeding the original image in resolution by creating new pixel value data between pixels, generating a high-frequency component, and sharpening the original image. In addition, the technique for incorporating a super-resolution function into a video input-output apparatus as described above is being developed.
However, when the process including such a sharpening technique (e.g., the aforementioned super-resolution technique) has been realized in an actual digital television, it has been found that the image processing might have an adverse effect, depending on the type of images.